1. Field of the Invention
The present invention concerns a coating machine in which a cartridge for filling a coating material is mounted detachably to a machine body provided with a coating martial atomizing mechanism.
2. Statement of Related Art
In coating of car bodies, coating materials using organic solvents are predominant, but it has been demanded to decrease volatile organic solvents that evolve in a great amount in the coating process with a view point of environment preservation and prevention of public pollution and, as a countermeasure, coating with aqueous coating materials has attracted attention.
For using an aqueous coating with no loss, it is preferred to apply coating by an electrostatic coating apparatus of high coating efficiency. However, since the aqueous coating material has low electric resistance tending to electrically conduct the rotary atomizing head and the ground of the electrostatic coating machine by way of a coating material flowing through a coating material supply system, insulation has to be applied over the entire coating material supply system to prevent leakage of high voltage of −60 to 90 kV applied to the rotary atomizing head.
Accordingly, a coating material is filled in a coating material tank formed in a coating machine or a coating material is filled in a cartridge mounted detachably to a coating machine and a coating martial is discharged under pressure from the coating material tank or the cartridge for coating thereby electrically shielding the coating material supply system in order not to leak a high voltage even when it is applied to the coating machine (refer to Japanese Unexamined Patent Publication No. 2000-317354)
By the way, since the cartridge is filled with a coating material usually by an amount necessary to coat one car body, cartridges have to be exchanged within a short period time from the completion of coating for a preceding car body being conveyed on a coating line till reaching of a succeeding car body and, accordingly, exchange for cartridges is automated.
In a case of exchanging cartridges for a coating machine provided with a coating material atomizing head at the front and provided with a cartridge mounting portion at the back of a machine body, an arm of a cartridge exchange robot is advanced just above a coating machine positioned to a cartridge exchange position with the mounting portion being upwarded to catch a used cartridge, which is extracted upwardly, retracted to a predetermined position and stored therein. Then a new cartridge is held to advance just above the coating machine and then displaced downwardly and enforced in the coating machine for loading.
That is, since the arm of the exchange robot has to move in different directions at least between a case of extracting a cartridge loaded on the coating machine or enforcing a new cartridge to conduct loading and unloading and a case of retracting the cartridge extracted from the coating machine or advancing a new cartridge just above the coating machine, the size of the exchange robot is enlarged to result in a problem of requiring a large exchange space along the coating line.
Further, since car bodies of different coating colors are conveyed together to a coating line, the coating machine has to be cleaned for color change on every exchange of cartridges and, accordingly, it is desired to further shorten the exchange time.
However, since the new cartridge can not be loaded unless the extracted used cartridge is stored, it takes a long time for exchange. When exchange is intended to conduct in a short period of time, it leads to a problem of requiring an exchange robot having an extracting robot arm and a loading robot arm separately, which enlarges the size of the robot per se and increases the cost.